Industrial process and apparatus



Jan. 23, 1968 J. R. TOWNSEND, JR 3,

I INDUSTRIAL PROCESS AND APPARATUS I Filed June 29, 1965 ATTORNEY JOSEPHR. TOWNSEND,JR.

United States Patent Ofiice 3,365,128 Patented Jan. 23, 1968 3,365,128INDUSTRIAL PROCESS AND APPARATUS Joseph R. Townsend, Jr., West Chester,Pa., assignor to Pennsalt Chemicals Corporation, Philadelphia, Pa., acorporation of Pennsylvania Filed June 29, 1965, Ser. No. 467,840 4Claims. (Cl. 233-21) This invention relates to centrifuges. Morespecifically this invention relates to centrifuges provided with meansfor discharging a separated fluid under positive pressure especiallywhere the discharging fluid is viscous.

The prior art relating to centrifuging is replete with innumerabledischarge devices for removing separated liquid from solid bowlmachines. A common expedient is simply the provision of a ring dam ortube darn over which the separated liquid may spill to the outside ofthe bowl for collection by a suitable cover device. Alternatively, askimmer tube dips into an inwardly facing trough or pocket mounted onthe centrifuge bowl and scoops the liquid as it races by. In a diiferentform the skimmer tube takes the shape of a paring disc which is disposedon the centrifuge axis and extends outwardly on all sides into thetrough or pocket. The paring disc is equipped with angled passages intowhich the liquid rushes as the centrifuge rotates. A suitable inwarddischarge channel for the disc is provided.

Difficulty has been experienced in the discharge of viscous fluids,either heavy or light, from the centrifuge by means of a paring disc.Certain fluids, such as the protein-fat mud phase in a corn syrupoperation, the heavy soap phase in vegetable oil refining,the lightphase cheese in a cream cheese operation, have defied discharge througha standard paring disc. Presumably this has been because the centrifugalhead in the paring trough or pocket has been insufficient to drive thefluid into the openings in the periphery of the paring disc. In order toovercome this difficulty, these fluids have been diluted to make themless viscous and more susceptible to discharge. While the dilution hasmade discharge through the paring device possible, it has presentedother problems: need for dilution injection equipment, need forsubsequent treatment of the discharged fluid to remove the diluent, etc.

I have found that the effectiveness of a conventional paring disc inoperation on difiicult-to-discharge fluids may be very greatly enhancedby a simple, yet unobvious modification to its structure. In themodification, portions of the vanes of the paring disc are laid bare byreducing the diameter of one of the side Walls of the disc. Portions ofthe vanes are thereby exposed. While this has no affect on the pressureof the liquid in the paring trough, it has made possible the dischargeof fluids through the paring disc which heretofore have not beenpossible to discharge. The explanation of the success is not certain,but apparently the vanes of the paring device being exposed in part forma kind of a scoop which serves to better direct the fluid into thechannels of the device and to thereby better communicate the pressure inthe trough into the device. On the other hand, the exposed vanes inbeing more prominent than the vanes of the conventional skimmer devicesof the prior art accentuates the difference in velocity of the fluid andthe paring device. This velocity is then converted into additional headby the paring device.

It is a feature of the invention therefore to provide for a centrifugehaving a viscous discharge fluid, an improved paring device whichefficiently discharges the fluid under pressure without the aid of adiluent.

Other features of the invention will be apparent from a review of thefollowing specification describing a preferred form of apparatus andreference to the drawings in which:

FIGURE 1 is a fragmentary sectional view of a centrifuge embodying theinvention;

FIGURE 2 is an enlarged sectional view taken on line 22 of FIGURE 1; and

FIGURE 3 is an enlarged sectional view of structure within section line33 of FIGURE 1.

Briefly, in a centrifuge having a discharge paringdevice comprising acircular structure with passages from its periphery to an inwarddischarge channel, the invention is the improvement of reducing thediameter of one of the side walls to expose portions of the vanes withinthe paring device.

Referring more specifically to the drawings, FIGURE 1 is a fragmentarysectional view of a centrifuge embodying the invention and generallydesignated 10. It comprises a bowl 12 mounted for rotation by asuspending and driving shaft 14. The bowl structure may include a set 16of frusto-conical discs which are disposed about a vaned center tube 16aand operate in the convention-a1 manner to increase the efliciency ofthe separation. The feed liquid is delivered to the lower end of thecentrifuge by feed means (not shown).

Mounted on the top of the bowl 12 is the heavy discharge housing 18 andthe light discharge housing 20. The housing 20 is supported on thedividing cone 22 secured between the upper end of the center tube 16aand the bowl top. In between the dividing cone 22 and housing 18 are aplurality of spaced ribs 24 which space the elements properly and permitpassage of the heavy liquid from the centrifuge bowl into a pocket 26facing inwardly and formed between the housings 18 arid 20. The ribswiden in the pocket 26 and comprise part of radial vanes 28 which assurerotation of the liquid Within the pocket 26 with the bowl.

The housing 20 together with the inward annular wall 30 also supportedon the dividing cone 22 forms a pocket 32 which is provided with vanes34. In operation separated light liquid from the centrifuge bowl spillsover the annular wall 30 into the pocket 32.

Surrounding the drive and supporting shaft 14 is a stationary dischargeassembly comprising the paring discs 36 and 38. The structure of theparing discs are comparable. As shown in FIGURE 2 the disc 36 is annularand provided with passages 37 which may be curved and extend from theperiphery of the device to an inward discharge channel 40. The channelis formed between the tubular exterior Wall 42 of the paring device 36and the tubular wall 44 of the lower paring device 38. Spacing ribs 46are provided to hold the two tubular portions in proper relation.

The lower paring device 38 similarly has extending inward from itsperiphery discharge passages 48 which extend to the inward dischargechannel 5%} between the tubular element 44 and the inner tubular element52. Ribs 54 hold these two parts in proper relative position.

The paring device assemblies are supported as shown on the centrifugecover which is stationary. The upper ends of the channels 46 and 50communicate respectively with discharge conduits 56 and 58 as shown.

Focusing now on the particular area of the invention, FIGURE 3 showsthat the lower paring disc 38 comprises a top wall 60 and a bottom wall62. The top wall may be provided with annular ribs 64 to reduceturbulence as described in patent application Ser. No. 419,086, filedDec. 17, 1964, by Leonard Shapiro. Such ribs 66 may also be on theparing disc 36. Vanes 68 (FIG. 3) are provided between the two walls andextend out to the periphery of the top wall. As shown the vanes may bearcuate in shape so as to smoothly direct the fluid into the dischargeannulus.

The under wall 62. of the paring device is reduced in diameter comparedto the upper wall by a distance a. In a disc having an 8 inch diameter,the distance a has been roughly 4 inch. Radial reductions of 5-l0% ofthe radius of the disc have been found eifective. This has exposed acorresponding area of the underface of the vanes.

It should be clear that the reduction in diameter might well be in theupper wall 60 instead of the lower, or indeed on one of the Walls of thedisc 36, if the viscous fluid is the heavy phase.

A splash shield 70 is provided on the underface of the paring device 36and also serves to control turbulence or splashing. Passages 72 throughthe paring disc 36 provide means for venting gas pressures which maydevelop on either side of the disc.

It should be understood that variations within the scope of theinvention are possible. For instance, the invention may be applied to acentrifuge having a horizontal axis and to the paring device of acentrifuge of an altogether different type, for instance a wormcentrifuge.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or central attributes thereof and,accordingly, reference should be made to the appended claims rather thanthe foregoing specifications as indicating the scope of the invention.

I claim:

1. A centrifuge bowl having an axis of rotation, an annular inwardlyfacing pocket mounted on the bowl concentric With the axis of rotationand receiving a discharge liquid from the bowl, the pocket having sidewalls extending inward to a radial level establishing a maximum depth ofliquid for the pocket, said pocket being free of means for introducingfluids thereto from outside said bowl for mixture with said liquid, astationary takeoff device having a circular outer periphery disposedconcentrically about the axis of rotation and extending outward into thepocket, the takeoff device having opposite substantially radial sidesand vanes between the sides extending outward to the periphery anddefining passages from the periphery into an inward takeoff conduit, theimprovement wherein one of said substantially radial sides is reduced inradius to expose portions of the radial faces of the vanes.

2. A centrifuge bowl as described in claim 1 wherein the radialreduction is 540% of the radius of the device.

3. A centrifuge bowl as described in claim 1 wherein said takeoff devicefurther includes at least one annularly extending rib on the other ofsaid radial sides adjacent the periphery thereof for reducing theturbulence of liquid contacted by said exposed portions of the radialfaces of the vanes.

4. A centrifuge bowl having a primary separating compartment and adischarge pocket separate from but connected with the primary separatingcompartment, said bowl receiving material to be centrifuged andseparating liquid therefrom for delivery to said pocket, said pocketbeing free of means for injecting fluids from outside said bowl intosaid liquid, a paring device in said discharge pocket and disposedconcentric with the axis of the bowl, the paring device extendingoutward into the pocket and comprising a pair of substantially radialside walls and vanes disposed between the side walls, one of the sidewalls terminating outwardly in a periphery inward of the periphery ofthe other side walls and the vanes.

References Cited FOREIGN PATENTS 481,711 3/1938 Great Britain.

HENRY T. KLINKSIEK, Primary Examiner.

1. A CENTRIFUGE BOWL HAVING AN AXIS OF ROTATION, AN ANNULAR INWARDLYFACING POCKET MOUNTED ON THE BOWL CONCENTRIC WITH THE AXIS OF ROTATIONAND RECEIVING A DISCHARGE LIQUID FROM THE BOWL, THE POCKET HAVING SIDEWALLS EXTENDING INWARD TO A RADIAL LEVEL ESTABLISHING A MAXIMUM DEPTH OFLIQUID FOR THE POCKET, SAID POCKET BEING FREE OF MEANS FOR INTRODUCINGFLUIDS THERETO FROM OUTSIDE SAID BOWL FOR MIXTURE WITH SAID LIQUID, ASTATIONARY TAKEOFF DEVIDE HAVING A CIRCULAR OUTER PERIPHERY DISPOSEDCONCENTRICALLY ABOUT THE AXIS OF ROTATION AND EXTENDING OUTWARD